1A. During exercise, PGC-1a is involved to a muscle fiber-type switch to the highly oxidative slow-twitch myofiber-type, suggesting a partial contribution of PGC-1a in cell differentiation. Exercise increases neurogenesis in rodents and non-human primates. Very recently, life-long neurogenesis was convincingly demonstrated in the granular layer of the human dentate gyrus, which is important for cognition. Like slow-twitch myofibers, neurons also depend on high levels of oxygen for ATP production through mitochondrial oxidative phorphorylation. In analogy, it had been suggested that PGC-1a might be involved in neurogenesis. To test this hypothesis, we generated several lentiviral vectors to express wild-type PGC-1a and select mutant proteins in human neural progenitor cells. Our recent results do not support the hypothesis that PGC-1a increases neurogenesis. Interestingly, PGC-1a did not support neural differentiation. Details of our study and potential mechanisms will be described in a communication. 1B. In a recently published collaborative study (Russell lab, UMD) we characterized a novel p35 isoform of PGC-1a, which interacts with PINK1 protein in mitochondria. A second study, which links PINK1 and p35 levels with energy metabolism in Alzheimers patients and in chemically induced diabetic mice is in progress. We have generated several lentiviral vectors that express a truncated PGC-1a protein (p40). We postulate that p40 shares structural and functional similarities with p35. These vectors will help characterize the origin of p35 and its functions in cell culture. The studies will provide insights into potential metabolic deficiencies believed to be associated with several neurodegenerative diseases and with diabetic peripheral neuropathy. 2. Our therapeutic gene delivery strategy shares key elements with the strategies that were used in the clinical trials described above. The main difference is the therapeutic transgene. We have developed lentiviral vectors that encode a newly designed cell-penetrating peptide, which can inhibit the hyperactivity of a Cdk5/p25 kinase complex that is associated with several neurodegenerative diseases including Alzheimers and Parkinsons disease. In vivo efficacy of the inhibitory peptide itself was first reported by Dr. Pant, NINDS, IRP. Our peptide delivery strategy is based on gene therapy by lentiviral vector-transduced hematopoietic stem cells (CD34). The strategy is to use these migratory cells as factories to constitutively express, secrete and deliver the peptide to affected target cells in the brain. CD34 cells were obtained from Dr. Trisler (UMD), who is expert in cell differentiation and hematopoietic stem cells. We were able to infect over 70% of these cells with our high titer, peptide-encoding lentiviral vector. Peptide expression was greatly increased after a promoter change. These stably transduced CD34 cells were expanded without interference by the peptide and maintained high expression levels. Co-expression of EGFP also allows cell sorting for high expressing cells, if necessary. Confirmation of the inhibitory activity of the secreted peptide is in progress. Expanded transduced CD34 cells will be transplanted into transgenic mouse disease models. Dr. Trisler has agreed to provide CD34 cells and to help with future intravenous transplantations into mice. Several transgene mice models of neurodegenerative disease will be considered.